Windage Shield Pilot Unit for Gas Turbine Engine Alignment
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Solution Overview
Problem
Gas turbine engines face challenges in maintaining alignment and minimizing stress between components with different thermal and mechanical expansion rates, particularly between the windage shield and fan disk, which can lead to harmful stresses and misalignment during operation.
Innovation Solution
A pilot unit is introduced, comprising a pilot mount, pilot anchor, and a bias link that elastically deforms to maintain alignment and distribute stress, ensuring the windage shield remains aligned with the fan disk by engaging the pilot receiver and axial surface, while the bias link absorbs differential expansion stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the windage shield is rigidly coupled to the fan disk, then alignment is maintained, but harmful stresses increase due to differential thermal and mechanical expansion
Solution Approach 1:
The coupling between the windage shield and fan disk is segmented into multiple functional elements: a pilot unit with pilot anchor and pilot receiver for alignment, a bias link for stress absorption, and a fastener for secure attachment. This segmentation allows each element to address specific requirements independently, maintaining alignment while reducing harmful stresses.
Solution Approach 2:
The pilot unit acts as an intermediary between the windage shield and fan disk, providing a dedicated alignment mechanism that decouples the alignment function from the stress-bearing function. The pilot anchor engages with the pilot receiver to maintain precise alignment while the bias link absorbs differential expansion stresses.
2Stress or pressure
If the windage shield is loosely coupled to the fan disk, then stress is reduced, but alignment is lost during operation
Solution Approach 1:
The coupling system is divided into distinct functional segments: the pilot unit handles alignment, the bias link manages stress absorption, and the fastener provides secure attachment. This segmentation allows the pilot unit to maintain alignment independently while the bias link reduces stress transmission.
Solution Approach 2:
The bias link is designed with specific geometric parameters (curved inner surface, flexible configuration) that allow it to change its mechanical properties under load. It provides rigid support when needed for alignment while allowing controlled deformation to absorb thermal and mechanical expansion differences, effectively changing its stiffness parameter dynamically.
3Stability of the object's composition
If a rigid connection is used between windage shield and fan disk, then alignment is maintained, but stress concentration occurs at the connection point
Solution Approach 1:
The connection system is segmented into multiple elements that distribute the load: the pilot anchor and pilot receiver provide alignment, the bias link distributes stress through its flexible connection, and the fastener secures the assembly. This segmentation prevents stress concentration by spreading forces across multiple connection points and mechanisms.
Solution Approach 2:
The pilot unit serves as an intermediary that separates the alignment function from the stress-bearing function. The pilot anchor engages with the pilot receiver to maintain alignment while the bias link acts as a stress-distributing intermediary between the windage shield and fan disk, preventing stress concentration at any single point.
4Stability of the object's composition
If thermal expansion is restrained, then alignment is maintained, but harmful stresses increase in the windage shield
Solution Approach 1:
The bias link is designed with geometric parameters that allow controlled thermal expansion and mechanical deformation. Its curved inner surface and flexible configuration enable it to change length and shape in response to temperature changes, accommodating thermal expansion of the windage shield while maintaining alignment through the pilot unit.
Solution Approach 2:
The coupling system transitions from a static rigid connection to a dynamic system where the bias link can deform and adjust during operation. The bias link's ability to elastically deform allows it to adapt to changing thermal and mechanical conditions, maintaining alignment while absorbing expansion stresses that would otherwise be harmful.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces stress on the windage shield and maintains alignment during operational temperature and speed changes, minimizing radial loads on the fastener and maintaining a constant distance between the pilot anchor and component anchor, thus enhancing the durability and efficiency of the gas turbine engine.
Implementation Method 1
a bias link arranged to extend between and interconnect the pilot mount and the pilot anchor. The bias link may be configured to provide means for maintaining a pilot-setting force between the pilot anchor and the pilot receiver when the second component is coupled to the first component to retain alignment of the first component with the second component for rotation about the rotational axis while minimizing stress formed in the bias link as a result of first component having a different thermal or mechanical expansion rate from the second component during operation of the gas turbine engine
Data Source
AI summary
A fan assembly for use in a gas turbine engine of an aircraft includes a fan disk having a number of fan blades and a windage shield coupled to the fan disk to move therewith. The fan assembly supplies air for use in the engine. The windage shield rotates with the fan disk during operation of the gas turbine engine and directs air supplied by the fan blade.